@spacecadet65 (love the name btw), if you picked up the triple mica black plate GE 5751, you've got a real winner, I have one of those as well. I also have a couple regular GE 5751 grey plate, they're pretty good too with a neutral, linear "softer" sound signature.
If you're volume pot is 9 o'clock and 90 dB speaker output, something is running with high gain. You could try attenuators on the amplifier inputs. Initially I could not get the Willsenton volume past 9 o'clock, 10 max with 99dB sensitive Klipsch Fortes. With 10dB attenuators I can now use more of the volume pot, the VU meters move more than a centimeter or two and no loss in sound quality, dynamics, rhythm pace or timing. Check out Parts Express, they have Harrison Labs in-line attenuators for RCA inputs. You can also find XLR attenuators if you're running fully balanced interconnects.
Another thing to consider is "tube synergy." What are the other tubes in the pre-amp circuit? The next stage in the Willsenton is two 6SN7s each driving a 300B which drive 845 output tubes. I've found mixing and matching the 12AX7/5751/12AT7 with certain 6SN7s can also make a sonic difference.
My favorite 6SN7 in the Willsenton are Tung Sol WGTA brown base JAN. Great combination of warmth, lots of detail and punch. Sylvania WGTs, WGTAs and WGTBs are more mellow, less detail but have a lot of warmth. RCAs are smoother, less detail, less warmth, but very neutral, linear frequency response and can stand a "hotter" 12AX7 to punch them up a notch. Raytheon WGTAs and WGTBs are a touch grainy, think guitar amp in overdrive, and marry better with a softer V1 like the GE 5751 or a Telefunken 12AT7.
I probably spend too much time swapping tubes in and out, but that is part of the fun of a good tube amp I guess.
